Furnace for heating metal wire



M. T'OMURA FURNACE FOR HEATING METAL WIRE Filed April 20, 1932 July 24, 1934.

MABANOBU TDMURA I INVENTOR m qM ATTORNEYS i atented July 24, 1934 UNITED STATES FURNACE FOR HEATING METAL WIRE Masanobu Tomura, Aoyama, Akasaka Kn,

Tokyo, Jap n Application April 20, 1932, Serial No. 606,344

2 Claims.

The present invention relates to a furnace for heating metal wire and has for its object to provide a furnace for directly heating the wire by a neutral or slightly reducing flame whereby oxi- 5 dization or cementation of the wire is prevented, the furnace being economical to construct and operate.

In the known metal wire heating furnaces, in order to prevent the oxidation of the wire due to heating a suitable number of long protective pipes or tunnels of refractory brick .extending from the front to the back of the furnace have been arranged in parallel on the hearth, and one or more wires run continuously in the said pipes or tunnels and heated indirectly from outside. However, as the said pipes or tunnels consist of many short lengths connected together, they are apt to have cracks produced at their joints during the operation. This permits combustion gas to enter through the cracks, thus oxidizing the wire and hindering the running of the wire on account of an accumulation of oxide. Also, there is the trouble of removing oxide from the wire and its surface becoming uneven. Moreover, the decrease of its weight deteriorates its quality. In this case, if the operation is made with reducing flame so as to prevent the oxidation, 9. large quantity of soot is produced owing to incomplete combustion and deposited upon the wire, making a subsequent pickling operation impossible. Further, the wire has its quality changed by the cementation.

Thus, the indirect heating demands a big sacrifice in the cost of the-construction as well as labor with uncertain effect, .as the wire is not protected perfectly from combustion gas. Moreover, the repair of such a furnace entails long discontinuation of the work and its reconstruction involves big expense.

Now, the fundamental cause of this dimculty is that as in the burning of fuel .oil smokeless burning cannot be expected without supplying a large amount of excessive oxygen, the presence of a more or less amount of free oxygen is unavoidable.

According to the present invention, a furnace for heating metal wire by the burning of heavy oil'is provided having a partition well constructed in a portion of the upper part of the furnace to form a combustion chamber between it and the roof of the furnace. The heavy oil spouted from a nozzle is volatilized in the said chamber by the conductive and radiant heat from the walls and mixes with a suitable amount of combustion air intimately and burns. The provision of this combustion-chamber enables a nice regulation of the proportion of fuel and air to be attained to produce a neutral or slightly reducing flame which does not contain free oxygen at all. The lower part and other end of the furnace chamber form a hating chamber, the lower surface of which is used as a floor for running the metal wire. The said neutral or reducing flame is conducted to the heating chamber to heat the wire directly. Under the said floor there is a flue serving to re- 66 ceive part of the combustion gases from the heating chamber and thus to heat the wire uniformly and directly on the heating floor.

Thus, as according to this invention the protective pipes or tunnels can be dispensed with, 70 big cost of equipment and repair can not only be saved, but also it is possible to increase the durability of the furnace and reduce the loss caused by the discontinuation of the work during repairing. Further, as fuel oil can be utilized with the highest efficiency, about 40% of it can be, saved as compared with the known furnace, and as there is no fear of the wire being oxidized or cemented or carbon being deposited on it, its quality is not injured, nor is its weight reduced.

Referring to the accompanying drawing which shows an example of carrying out this invention,

Fig. 1 is a longitudinal sectional view showing the construction of the interior of this furnace;

Fig. 2, the front elevation;

Figs. 3 and 4, cross sections of Fig. 1 on lines IIIIII and IVIV, respectively, and

Fig. 5 a longitudinal section of Fig. 1 on line VV.

Throughout the views, the same reference nu- 9o merals indicate the same or like parts.

In the-drawing, 1 is a furnace body,- 2 an inlet nozzle for fuel oil, 3 a combustion chamber, 4 partition wall between the combustion chamber and heating chamber, and 5 a heating chamber. 6 is 'a charging floor provided with a number of U-shaped channels 7 to prevent theconfusion of the running wires, and His 9. flue serving as a regenerator constructed under the charging floor. The wire 8 enters from the opening (a) of the U- shaped channel at the front and goes out, running continually, from the opening (b) atthe back. The fuel oil together with a suitable amount of air enters the combustion chamber 3 from the nozzle 2. The combustion chamber has suitable height, breadth and length and its wall surface is heated strongly by the flame, so the oil is burned completely and does not contain free oxygen at all and enters the heating chamber 5' as a slightlyreducing or neutral flame. Therefore, the flame 110 which has entered the heating chamber 5 never oxidizes the wire, nor does it cement the wire. Also, as it is smokeless, no carbon is deposited.

The following is an analytical table of the combustion gas in this case:--

Percent Free oxygen. None Carbon dioxide 13-15 Carbon monoxide 1- 3 The combustion gas which has entered the heating chamber 5, when used for preheating, passes through the passage 11 which also serves as a regenerator utilizing the excess of heat, from the right and left outlet ports 9 and 10 near the rear end of the furnace, preheating the interior of the furnace and goes out from the flue 12, giving the excess of heat sufficiently to the charging floor 6 from under it. However, in the operation the communication of the flue 12 with the combustion gas is cut off to only such an extent as to allow exhaust, the greater part of the gas being discharged out of the furnace from the front and back openings ((1) and (b) of the U-shaped channel 7. As regards the back opening (b), it is situated near the outlet ports 9 and 10 and consequently receives their sucking influence and moreover as the pressure is reduced by the inclination of the wall surface of the rear part of the heating chamber, the amount of the combustion gas exhausted is small and the majority of it flows in the counter direction to the path of the wire and goes out of the furnace from the front opening (a), heating the said wire directly. Then,

it comes into contact with air and burns with blue flame.

I claim:

I. .A furnace for heating metal wire comprising a chamber having a floor on which the wire may be moved continuously from one end of the furnace to the other, a substantially horizontal partition wall restricted to the front end of the furnace and extending upward to a level between the floor and the roof to form a combustion chamber in the upper partition of the furnace, said combustion chamber having an opening to admit fuel, a flue extending beneath said floor and ports in the rear end of the furnace communicating with said flue.

2. A furnace for the direct heating of metal wire comprising an elongated chamber having a floor provided with a plurality of longitudinal grooves respectively to receive wires which may be moved continuously from one end of the furnace to the other, a substantially horizontal partition wall restricted to the front end of thefurnace and extending upward to a level between the floor and the roof to form a combustion chamber in the upper portion of the furnace, said combustion chamber being provided with an opening to admit fuel, a line extending beneath said floor and ports inv the rear end of the furnace communicating with said flue.

MASANOBU TOMURA. 

